Better pictures would be appreciated for an ID, but the 2 most likely candidates based on the markings are a Zygiella species (but the body looks a bit long, I had a large female have a good go at biting me whilst I was handling her, with no obvious result), or a Metellina species (more likely, google M. segmentata & compare).

The venom in either case is unlikely to be significant, however spiders eat flies..both, therefore, can carry bacteria and you should seek medical attention if there are any signs of infection (antibiotics are usually prescribed).